An electric power system is a complex interconnection of many components. Customers switch their loads on and off independently, causing feeder loading levels to vary over time. Utility apparatus connected to these feeders also operate from time to time, to maintain proper delivery of service to customers and to protect equipment. All of these contribute to continuous variations in feeder loading levels and electrical characteristics. Some electrical changes indicate system conditions that need immediate attention to prevent further damage to the system or connected equipment, to restore service, etc. Other changes indicate conditions that are suboptimal and that should be addressed at the utility's earliest convenience. Still others indicate normal system operation and may not need any specific attention unless the utility or its customers experience an unusual condition whose solution may be aided by knowledge about normal operations of the system.
Operations and maintenance (O&M) personnel often lack data and information that would help them perform their functions better. Conversely some modern systems can provide so much information that personnel become overwhelmed, and this situation also negatively affects their ability to perform their functions optimally. Thus having too much information arguably can be as bad as having too little.
A related difficulty in receiving and using information in optimal ways has to do with communication system typically available in substations and even more especially at remote points on feeders. In situations in which substations are unmanned, information has to be provided to operations personnel elsewhere before those personnel can respond. If monitoring equipment is located somewhere other than the substation (e.g., on a pole somewhere between the substation and end users), the quality of communications generally is even lower than at substations. During normal operations the amount of data that modern monitoring equipment can collect in a substation is substantial. Communication channels to substations often have very limited capacity and can take a significant amount of time to transmit information, even during normal operating conditions.
When abnormal conditions (e.g., when a piece of equipment begins to fail or when a fault occurs) occur, the amount of information can get even larger. This can affect the ability of operations personnel to receive and act upon information in a timely way. If information is simply transmitted in the order in which it is collected, operator notification of critical events may be delayed while awaiting the transmission of relatively unimportant information to finish. It would be better for critical information to be transmitted first, with transmission of relatively unimportant information being postponed. Some utilities may not want certain types of relatively unimportant, routine information to ever be sent to operations and maintenance personnel, except in special circumstances in which they are performing some type of special study or troubleshooting.